int wctlp_set_coltypes(wctlp *lp, char sense) {
int nvars, i, val = 0;
char isense;
switch (sense) {
case wctlp_CONT:
isense = GRB_CONTINUOUS;
break;
case wctlp_BIN:
isense = GRB_BINARY;
break;
case wctlp_INT:
isense = GRB_INTEGER;
break;
default:
fprintf(stderr, "Unknown variable sense: %c\n", sense);
val = 1;
return val;
}
val = GRBgetintattr(lp->model, GRB_INT_ATTR_NUMVARS, &nvars);
CHECK_VAL_GRB(val, "Failed to get number of variables", lp->env);
for (i = 0; i < nvars; ++i) {
val = GRBsetcharattrelement(lp->model, GRB_CHAR_ATTR_VTYPE, i, isense);
CHECK_VAL_GRB(val , "Failed to set variable types", lp->env);
}
val = GRBupdatemodel(lp->model);
CHECK_VAL_GRB(val, "Failed to update model", lp->env);
return val;
}
int wctlp_addcol(wctlp *lp, int nzcount, int *cind , double *cval,
double obj, double lb, double ub, char sense, char *name) {
int val = 0;
char isense;
switch (sense) {
case wctlp_CONT:
isense = GRB_CONTINUOUS;
break;
case wctlp_BIN:
isense = GRB_BINARY;
break;
case wctlp_INT:
isense = GRB_INTEGER;
break;
default:
fprintf(stderr, "Unknown variable sense: %c\n", sense);
val = 1;
return val;
}
val = GRBaddvar(lp->model, nzcount, cind, cval, obj, lb, ub, isense, name);
CHECK_VAL_GRB(val, "Failed adding GRBaddvar", lp->env);
val = GRBupdatemodel(lp->model);
CHECK_VAL_GRB(val, "Failed updating the model", lp->env);
return val;
}
void gurobi_addvars(int32_t n, int32_t m) {
double *lb;
int i;
int error;
char *vtype;
NumVars = n+m;
ind = (int *)malloc((n+m) * sizeof(int));
Val = (double *)malloc((n+m) * sizeof(double));
ValIndex = 0;
lb = (double *)malloc((n+m) * sizeof(double));
vtype = (char *)malloc((n+m) * sizeof(char));
for (i=0; i<n+m; i++) {
ind[i] = i;
lb[i] = - GRB_INFINITY;
vtype[i] = (i<n) ? GRB_CONTINUOUS : GRB_INTEGER;
}
error = GRBaddvars(model, n+m, 0, NULL, NULL, NULL, NULL, lb, NULL, vtype, NULL);
ERRORCHECK(error);
error = GRBupdatemodel(model);
ERRORCHECK(error);
#ifdef DEBUG
gurobi_cfprintf(stderr, "successfully exiting gurobi_addvars, n = %d\n", n);
#endif
}
int wctlp_addrow(wctlp *lp, int nzcount, int *cind , double *cval,
char sense, double rhs, char *name) {
int val = 0;
char isense;
switch (sense) {
case wctlp_EQUAL:
isense = GRB_EQUAL;
break;
case wctlp_LESS_EQUAL:
isense = GRB_LESS_EQUAL;
break;
case wctlp_GREATER_EQUAL:
isense = GRB_GREATER_EQUAL;
break;
default:
fprintf(stderr, "Unknown variable sense: %c\n", sense);
val = 1;
return val;
}
val = GRBaddconstr(lp->model, nzcount, cind, cval, isense, rhs, name);
CHECK_VAL_GRB(val, "Failed GRBadd", lp->env);
val = GRBupdatemodel(lp->model);
CHECK_VAL_GRB(val, "Failed updating the model", lp->env);
return val;
}
int wctlp_change_obj(wctlp *lp, int start, int len, double *values) {
int val = 0;
val = GRBsetdblattrarray(lp->model, GRB_DBL_ATTR_OBJ, start, len, values);
CHECK_VAL_GRB(val, "Failed in GRBsetdblattrarray", lp->env);
val = GRBupdatemodel(lp->model);
CHECK_VAL_GRB(val, "Failed to update model", lp->env);
return val;
}
int wctlp_setbound(wctlp *lp, int col, char lb_or_ub, double bound) {
int val = 0;
if (lb_or_ub == 'L') {
val = GRBsetdblattrelement(lp->model, GRB_DBL_ATTR_LB, col, bound);
} else {
val = GRBsetdblattrelement(lp->model, GRB_DBL_ATTR_UB, col, bound);
}
CHECK_VAL_GRB(val, "Failed to set bound", lp->env);
val = GRBupdatemodel(lp->model);
CHECK_VAL_GRB(val, "Failed to update model", lp->env);
return val;
}
int wctlp_deletecols(wctlp *lp, int first, int last) {
int val = 0;
int *dellist = (int *) NULL;
int ndel = last - first + 1 ;
int i;
dellist = CC_SAFE_MALLOC(ndel, int);
CCcheck_NULL_2(dellist, "Failed to allocated memory to dellist");
for (i = 0; i < ndel; ++i) {
dellist[i] = first + i;
}
val = GRBdelvars(lp->model, ndel, dellist);
CHECK_VAL_GRB2(val, "Failed to delete cols", lp->env);
GRBupdatemodel(lp->model);
CHECK_VAL_GRB2(val, "Failed to update the model", lp->env);
CLEAN:
CC_IFFREE(dellist, int);
return val;
}
void GurobiInterface::
eval(void* mem, const double** arg, double** res, int* iw, double* w) const {
auto m = static_cast<GurobiMemory*>(mem);
// Inputs
const double *h=arg[CONIC_H],
*g=arg[CONIC_G],
*a=arg[CONIC_A],
*lba=arg[CONIC_LBA],
*uba=arg[CONIC_UBA],
*lbx=arg[CONIC_LBX],
*ubx=arg[CONIC_UBX],
*x0=arg[CONIC_X0],
*lam_x0=arg[CONIC_LAM_X0];
// Outputs
double *x=res[CONIC_X],
*cost=res[CONIC_COST],
*lam_a=res[CONIC_LAM_A],
*lam_x=res[CONIC_LAM_X];
// Temporary memory
double *val=w; w+=nx_;
int *ind=iw; iw+=nx_;
int *ind2=iw; iw+=nx_;
int *tr_ind=iw; iw+=nx_;
// Greate an empty model
GRBmodel *model = 0;
try {
int flag = GRBnewmodel(m->env, &model, name_.c_str(), 0, 0, 0, 0, 0, 0);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
// Add variables
for (int i=0; i<nx_; ++i) {
// Get bounds
double lb = lbx ? lbx[i] : 0., ub = ubx ? ubx[i] : 0.;
if (isinf(lb)) lb = -GRB_INFINITY;
if (isinf(ub)) ub = GRB_INFINITY;
// Get variable type
char vtype;
if (!vtype_.empty()) {
// Explicitly set 'vtype' takes precedence
vtype = vtype_.at(i);
} else if (!discrete_.empty() && discrete_.at(i)) {
// Variable marked as discrete (integer or binary)
vtype = lb==0 && ub==1 ? GRB_BINARY : GRB_INTEGER;
} else {
// Continious variable
vtype = GRB_CONTINUOUS;
}
// Pass to model
flag = GRBaddvar(model, 0, 0, 0, g ? g[i] : 0., lb, ub, vtype, 0);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
}
flag = GRBupdatemodel(model);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
// Add quadratic terms
const int *H_colind=sparsity_in(CONIC_H).colind(), *H_row=sparsity_in(CONIC_H).row();
for (int i=0; i<nx_; ++i) {
// Quadratic term nonzero indices
int numqnz = H_colind[1]-H_colind[0];
casadi_copy(H_row, numqnz, ind);
H_colind++;
H_row += numqnz;
// Corresponding column
casadi_fill(ind2, numqnz, i);
// Quadratic term nonzeros
if (h) {
casadi_copy(h, numqnz, val);
casadi_scal(numqnz, 0.5, val);
h += numqnz;
} else {
casadi_fill(val, numqnz, 0.);
}
// Pass to model
flag = GRBaddqpterms(model, numqnz, ind, ind2, val);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
}
// Add constraints
const int *A_colind=sparsity_in(CONIC_A).colind(), *A_row=sparsity_in(CONIC_A).row();
casadi_copy(A_colind, nx_, tr_ind);
for (int i=0; i<na_; ++i) {
// Get bounds
double lb = lba ? lba[i] : 0., ub = uba ? uba[i] : 0.;
// if (isinf(lb)) lb = -GRB_INFINITY;
// if (isinf(ub)) ub = GRB_INFINITY;
// Constraint nonzeros
int numnz = 0;
for (int j=0; j<nx_; ++j) {
if (tr_ind[j]<A_colind[j+1] && A_row[tr_ind[j]]==i) {
ind[numnz] = j;
val[numnz] = a ? a[tr_ind[j]] : 0;
numnz++;
tr_ind[j]++;
}
}
// Pass to model
if (isinf(lb)) {
if (isinf(ub)) {
// Neither upper or lower bounds, skip
} else {
// Only upper bound
flag = GRBaddconstr(model, numnz, ind, val, GRB_LESS_EQUAL, ub, 0);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
}
} else {
if (isinf(ub)) {
// Only lower bound
flag = GRBaddconstr(model, numnz, ind, val, GRB_GREATER_EQUAL, lb, 0);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
} else if (lb==ub) {
// Upper and lower bounds equal
flag = GRBaddconstr(model, numnz, ind, val, GRB_EQUAL, lb, 0);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
} else {
// Both upper and lower bounds
flag = GRBaddrangeconstr(model, numnz, ind, val, lb, ub, 0);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
}
}
}
// Solve the optimization problem
flag = GRBoptimize(model);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
int optimstatus;
flag = GRBgetintattr(model, GRB_INT_ATTR_STATUS, &optimstatus);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
// Get the objective value, if requested
if (cost) {
flag = GRBgetdblattr(model, GRB_DBL_ATTR_OBJVAL, cost);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
}
// Get the optimal solution, if requested
if (x) {
flag = GRBgetdblattrarray(model, GRB_DBL_ATTR_X, 0, nx_, x);
casadi_assert_message(!flag, GRBgeterrormsg(m->env));
}
// Free memory
GRBfreemodel(model);
} catch (...) {
// Free memory
if (model) GRBfreemodel(model);
throw;
}
}
int engine(int numassets, int numfactors,
double *ub, double *lb, double *mu, double *sigma2,
double *V, double *F, double lambda)
{
int retcode = 0;
GRBenv *env = NULL;
GRBmodel *model = NULL;
int n, i, j, k;
double *x;
int *qrow, *qcol, Nq;
double *qval;
int *cind;
double rhs;
char sense;
double *cval;
int numnonz;
char **names, bigname[100];
double expectedreturnval;
printf("running solver engine\n");
n = numassets + numfactors;
retcode = GRBloadenv(&env, "engine.log");
if (retcode) goto BACK;
/* Create initial model */
retcode = GRBnewmodel(env, &model, "factors", n,
NULL, NULL, NULL, NULL, NULL);
if (retcode) goto BACK;
names = (char **) calloc(n, sizeof(char *));
/** next we create the remaining attributes for the n columns **/
x = (double *) calloc (n, sizeof(double));
for(j = 0; j < numassets; j++){
names[j] = (char *)calloc(3, sizeof(char));
if(names[j] == NULL){
retcode = 1; goto BACK;
}
sprintf(names[j],"x%d", j);
}
for(j = numassets; j < numassets + numfactors; j++){
names[j] = (char *)calloc(3, sizeof(char));
if(names[j] == NULL){
retcode = 1; goto BACK;
}
sprintf(names[j],"F%d", j - numassets);
}
/* initialize variables */
for(j = 0; j < n; j++){
retcode = GRBsetstrattrelement(model, "VarName", j, names[j]);
if (retcode) goto BACK;
retcode = GRBsetdblattrelement(model, "Obj", j, -mu[j]);
if (retcode) goto BACK;
retcode = GRBsetdblattrelement(model, "LB", j, lb[j]);
if (retcode) goto BACK;
retcode = GRBsetdblattrelement(model, "UB", j, ub[j]);
if (retcode) goto BACK;
}
/** next, the quadratic -- there are numassets + numfactors*numfactors nonzeroes:
numassets residual variances plus the numfactors x numfactors
factor covariance matrix**/
Nq = numassets + numfactors*numfactors;
qrow = (int *) calloc(Nq, sizeof(int)); /** row indices **/
qcol = (int *) calloc(Nq, sizeof(int)); /** column indices **/
qval = (double *) calloc(Nq, sizeof(double)); /** values **/
if( ( qrow == NULL) || ( qcol == NULL) || (qval == NULL) ){
printf("could not create quadratic\n");
retcode = 1; goto BACK;
}
for (j = 0; j < numassets; j++){
qval[j] = lambda*sigma2[j];
qrow[j] = qcol[j] = j;
}
for (i = 0; i < numfactors; i++){
for (j = 0; j < numfactors; j++){
k = i*numfactors + j;
qval[k + numassets] = lambda*F[k];
qrow[k + numassets] = numassets + i;
qcol[k + numassets] = numassets + j;
}
}
retcode = GRBaddqpterms(model, Nq, qrow, qcol, qval);
if (retcode) goto BACK;
/** now we will add one constraint at a time **/
/** we need to have a couple of auxiliary arrays **/
cind = (int *)calloc(n, sizeof(int)); /** n is over the top since no constraint is totally dense; but it's not too bad here **/
cval= (double *)calloc(n, sizeof(double));
if(!cval){
printf("cannot allocate cval\n"); retcode = 2; goto BACK;
}
for(i = 0; i < numfactors; i++){
for(j = 0; j < numassets; j++){
cval[j] = V[i*numassets + j];
cind[j] = j;
}
cind[numassets] = /* j */ numassets + i;
cval[numassets] = -1;
numnonz = numassets + 1;
rhs = 0;
sense = GRB_EQUAL;
sprintf(bigname,"factor%d",i);
retcode = GRBaddconstr(model, numnonz, cind, cval, sense, rhs, bigname);
if (retcode) goto BACK;
}
/** sum of x variables = 1 **/
for (j = 0; j < numassets; j++){
cval[j] = 1.0; cind[j] = j;
}
numnonz = numassets;
rhs = 1.0;
sense = GRB_EQUAL;
/* let's reuse some space */
sprintf(bigname, "sum");
retcode = GRBaddconstr(model, numnonz, cind, cval, sense, rhs, bigname);
if (retcode) goto BACK;
retcode = GRBupdatemodel(model);
if (retcode) goto BACK;
/** optional: write the problem **/
retcode = GRBwrite(model, "engine.lp");
if (retcode) goto BACK;
retcode = GRBoptimize(model);
if (retcode) goto BACK;
/** get solution **/
retcode = GRBgetdblattrarray(model,
GRB_DBL_ATTR_X, 0, n,
x);
if(retcode) goto BACK;
/** now let's see the values **/
expectedreturnval = 0;
for(j = 0; j < numassets; j++){
if( x[j] > 1.0e-09){
printf("%s = %g\n", names[j], x[j]);
expectedreturnval += x[j]*mu[j];
}
}
printf("\n*** expected portfolio return: %g\n", expectedreturnval);
GRBfreemodel(model);
GRBfreeenv(env);
BACK:
printf("engine exits with code %d\n", retcode);
return retcode;
}
int
main(int argc,
char *argv[])
{
GRBenv *env = NULL;
GRBmodel *model = NULL;
int error = 0;
double sol[3];
int ind[3];
double val[3];
double obj[] = {1, 0, 0};
int qrow[3];
int qcol[3];
double qval[3];
int optimstatus;
double objval;
/* Create environment */
error = GRBloadenv(&env, "qcp.log");
if (error || env == NULL) {
fprintf(stderr, "Error: could not create environment\n");
exit(1);
}
/* Create an empty model */
error = GRBnewmodel(env, &model, "qcp", 0, NULL, NULL, NULL, NULL, NULL);
if (error) goto QUIT;
/* Add variables */
error = GRBaddvars(model, 3, 0, NULL, NULL, NULL, obj, NULL, NULL, NULL,
NULL);
if (error) goto QUIT;
/* Change sense to maximization */
error = GRBsetintattr(model, GRB_INT_ATTR_MODELSENSE, GRB_MAXIMIZE);
if (error) goto QUIT;
/* Integrate new variables */
error = GRBupdatemodel(model);
if (error) goto QUIT;
/* Linear constraint: x + y + z = 1 */
ind[0] = 0; ind[1] = 1; ind[2] = 2;
val[0] = 1; val[1] = 1; val[2] = 1;
error = GRBaddconstr(model, 3, ind, val, GRB_EQUAL, 1.0, "c0");
if (error) goto QUIT;
/* Cone: x^2 + y^2 <= z^2 */
qrow[0] = 0; qcol[0] = 0; qval[0] = 1.0;
qrow[1] = 1; qcol[1] = 1; qval[1] = 1.0;
qrow[2] = 2; qcol[2] = 2; qval[2] = -1.0;
error = GRBaddqconstr(model, 0, NULL, NULL, 3, qrow, qcol, qval,
GRB_LESS_EQUAL, 0.0, "qc0");
if (error) goto QUIT;
/* Rotated cone: x^2 <= yz */
qrow[0] = 0; qcol[0] = 0; qval[0] = 1.0;
qrow[1] = 1; qcol[1] = 2; qval[1] = -1.0;
error = GRBaddqconstr(model, 0, NULL, NULL, 2, qrow, qcol, qval,
GRB_LESS_EQUAL, 0.0, "qc1");
if (error) goto QUIT;
/* Optimize model */
error = GRBoptimize(model);
if (error) goto QUIT;
/* Write model to 'qcp.lp' */
error = GRBwrite(model, "qcp.lp");
if (error) goto QUIT;
/* Capture solution information */
error = GRBgetintattr(model, GRB_INT_ATTR_STATUS, &optimstatus);
if (error) goto QUIT;
error = GRBgetdblattr(model, GRB_DBL_ATTR_OBJVAL, &objval);
if (error) goto QUIT;
error = GRBgetdblattrarray(model, GRB_DBL_ATTR_X, 0, 3, sol);
if (error) goto QUIT;
printf("\nOptimization complete\n");
if (optimstatus == GRB_OPTIMAL) {
printf("Optimal objective: %.4e\n", objval);
printf(" x=%.2f, y=%.2f, z=%.2f\n", sol[0], sol[1], sol[2]);
} else if (optimstatus == GRB_INF_OR_UNBD) {
printf("Model is infeasible or unbounded\n");
} else {
printf("Optimization was stopped early\n");
}
QUIT:
/* Error reporting */
if (error) {
printf("ERROR: %s\n", GRBgeterrormsg(env));
exit(1);
}
/* Free model */
GRBfreemodel(model);
/* Free environment */
GRBfreeenv(env);
return 0;
}
int
main(int argc,
char *argv[])
{
GRBenv *env = NULL;
GRBmodel *model = NULL;
int i, j, len, n, solcount;
int error = 0;
char name[100];
double *x = NULL;
double *y = NULL;
int *ind = NULL;
double *val = NULL;
struct callback_data mydata;
if (argc < 2) {
fprintf(stderr, "Usage: tsp_c size\n");
exit(1);
}
n = atoi(argv[1]);
if (n == 0) {
fprintf(stderr, "Argument must be a positive integer.\n");
} else if (n > 30) {
printf("It will be a challenge to solve a TSP this large.\n");
}
x = (double *) malloc(n*sizeof(double));
y = (double *) malloc(n*sizeof(double));
ind = (int *) malloc(n*sizeof(int));
val = (double *) malloc(n*sizeof(double));
if (x == NULL || y == NULL || ind == NULL || val == NULL) {
fprintf(stderr, "Out of memory\n");
exit(1);
}
/* Create random points */
for (i = 0; i < n; i++) {
x[i] = ((double) rand())/RAND_MAX;
y[i] = ((double) rand())/RAND_MAX;
}
/* Create environment */
error = GRBloadenv(&env, "tsp.log");
if (error || env == NULL) {
fprintf(stderr, "Error: could not create environment\n");
exit(1);
}
/* Create an empty model */
error = GRBnewmodel(env, &model, "tsp", 0, NULL, NULL, NULL, NULL, NULL);
if (error) goto QUIT;
/* Add variables - one for every pair of nodes */
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
sprintf(name, "x_%d_%d", i, j);
error = GRBaddvar(model, 0, NULL, NULL, distance(x, y, i, j),
0.0, 1.0, GRB_BINARY, name);
if (error) goto QUIT;
}
}
/* Integrate new variables */
error = GRBupdatemodel(model);
if (error) goto QUIT;
/* Degree-2 constraints */
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
ind[j] = i*n+j;
val[j] = 1.0;
}
sprintf(name, "deg2_%d", i);
error = GRBaddconstr(model, n, ind, val, GRB_EQUAL, 2, name);
if (error) goto QUIT;
}
/* Forbid edge from node back to itself */
for (i = 0; i < n; i++) {
error = GRBsetdblattrelement(model, GRB_DBL_ATTR_UB, i*n+i, 0);
if (error) goto QUIT;
}
/* Symmetric TSP */
for (i = 0; i < n; i++) {
for (j = 0; j < i; j++) {
ind[0] = i*n+j;
ind[1] = i+j*n;
val[0] = 1;
val[1] = -1;
error = GRBaddconstr(model, 2, ind, val, GRB_EQUAL, 0, NULL);
if (error) goto QUIT;
}
}
/* Set callback function */
mydata.n = n;
error = GRBsetcallbackfunc(model, subtourelim, (void *) &mydata);
if (error) goto QUIT;
/* Turn off dual reductions - required when using lazy constraints */
error = GRBsetintparam(GRBgetenv(model), GRB_INT_PAR_DUALREDUCTIONS, 0);
if (error) goto QUIT;
/* Optimize model */
error = GRBoptimize(model);
if (error) goto QUIT;
/* Extract solution */
error = GRBgetintattr(model, GRB_INT_ATTR_SOLCOUNT, &solcount);
if (error) goto QUIT;
if (solcount > 0) {
int *tour = NULL;
double *sol = NULL;
sol = (double *) malloc(n*n*sizeof(double));
tour = (int *) malloc(n*sizeof(int));
if (sol == NULL || tour == NULL) {
fprintf(stderr, "Out of memory\n");
exit(1);
}
error = GRBgetdblattrarray(model, GRB_DBL_ATTR_X, 0, n*n, sol);
if (error) goto QUIT;
/* Print tour */
findsubtour(n, sol, &len, tour);
printf("Tour: ");
for (i = 0; i < len; i++)
printf("%d ", tour[i]);
printf("\n");
free(tour);
free(sol);
}
QUIT:
/* Free data */
free(x);
free(y);
free(ind);
free(val);
/* Error reporting */
if (error) {
printf("ERROR: %s\n", GRBgeterrormsg(env));
exit(1);
}
/* Free model */
GRBfreemodel(model);
/* Free environment */
GRBfreeenv(env);
return 0;
}
int
main(int argc,
char *argv[])
{
GRBenv *env = NULL;
GRBmodel *model = NULL;
int error = 0;
double sol[3];
int ind[3];
double val[3];
double obj[3];
char vtype[3];
int optimstatus;
double objval;
/* Create environment */
error = GRBloadenv(&env, "mip1.log");
if (error || env == NULL) {
fprintf(stderr, "Error: could not create environment\n");
exit(1);
}
/* Create an empty model */
error = GRBnewmodel(env, &model, "mip1", 0, NULL, NULL, NULL, NULL, NULL);
if (error) goto QUIT;
/* Add variables */
obj[0] = -1; obj[1] = -1; obj[2] = -2;
vtype[0] = GRB_BINARY; vtype[1] = GRB_BINARY; vtype[2] = GRB_BINARY;
error = GRBaddvars(model, 3, 0, NULL, NULL, NULL, obj, NULL, NULL, vtype,
NULL);
if (error) goto QUIT;
/* Integrate new variables */
error = GRBupdatemodel(model);
if (error) goto QUIT;
/* First constraint: x + 2 y + 3 z <= 4 */
ind[0] = 0; ind[1] = 1; ind[2] = 2;
val[0] = 1; val[1] = 2; val[2] = 3;
error = GRBaddconstr(model, 3, ind, val, GRB_LESS_EQUAL, 4.0, "c0");
if (error) goto QUIT;
/* Second constraint: x + y >= 1 */
ind[0] = 0; ind[1] = 1;
val[0] = 1; val[1] = 1;
error = GRBaddconstr(model, 2, ind, val, GRB_GREATER_EQUAL, 1.0, "c1");
if (error) goto QUIT;
/* Optimize model */
error = GRBoptimize(model);
if (error) goto QUIT;
/* Write model to 'mip1.lp' */
error = GRBwrite(model, "mip1.lp");
if (error) goto QUIT;
/* Capture solution information */
error = GRBgetintattr(model, GRB_INT_ATTR_STATUS, &optimstatus);
if (error) goto QUIT;
error = GRBgetdblattr(model, GRB_DBL_ATTR_OBJVAL, &objval);
if (error) goto QUIT;
error = GRBgetdblattrarray(model, GRB_DBL_ATTR_X, 0, 3, sol);
if (error) goto QUIT;
printf("\nOptimization complete\n");
if (optimstatus == GRB_OPTIMAL) {
printf("Optimal objective: %.4e\n", objval);
printf(" x=%.0f, y=%.0f, z=%.0f\n", sol[0], sol[1], sol[2]);
} else if (optimstatus == GRB_INF_OR_UNBD) {
printf("Model is infeasible or unbounded\n");
} else {
printf("Optimization was stopped early\n");
}
QUIT:
/* Error reporting */
if (error) {
printf("ERROR: %s\n", GRBgeterrormsg(env));
exit(1);
}
/* Free model */
GRBfreemodel(model);
/* Free environment */
GRBfreeenv(env);
return 0;
}
void gurobi_updatemodel(void) {
int error;
error = GRBupdatemodel(model);
ERRORCHECK(error);
}
int
main(int argc,
char *argv[])
{
GRBenv *env = NULL;
GRBmodel *model = NULL;
int error = 0, status;
int s, w, col;
int *cbeg = NULL;
int *cind = NULL;
int idx;
double *cval = NULL;
char *sense = NULL;
char vname[MAXSTR];
double obj;
int i, j, numvars, numconstrs;
int *vbeg = NULL;
int *vind = NULL;
double *vval = NULL;
double *vobj = NULL;
double sol;
char *cname, *sname;
int varnamesct = 0;
char **varnames = NULL;
/* Sample data */
const int nShifts = 14;
const int nWorkers = 7;
/* Sets of days and workers */
char* Shifts[] =
{ "Mon1", "Tue2", "Wed3", "Thu4", "Fri5", "Sat6",
"Sun7", "Mon8", "Tue9", "Wed10", "Thu11", "Fri12", "Sat13",
"Sun14" };
char* Workers[] =
{ "Amy", "Bob", "Cathy", "Dan", "Ed", "Fred", "Gu" };
/* Number of workers required for each shift */
double shiftRequirements[] =
{ 3, 2, 4, 4, 5, 6, 5, 2, 2, 3, 4, 6, 7, 5 };
/* Amount each worker is paid to work one shift */
double pay[] = { 10, 12, 10, 8, 8, 9, 11 };
/* Worker availability: 0 if the worker is unavailable for a shift */
double availability[][14] =
{ { 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1 },
{ 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0 },
{ 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1 },
{ 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1 },
{ 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1 },
{ 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1 },
{ 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 } };
/* Create environment */
error = GRBloadenv(&env, "workforce3.log");
if (error || env == NULL)
{
fprintf(stderr, "Error: could not create environment\n");
exit(1);
}
/* Create initial model */
error = GRBnewmodel(env, &model, "workforce3", nWorkers * nShifts,
NULL, NULL, NULL, NULL, NULL);
if (error) goto QUIT;
/* Initialize assignment decision variables:
x[w][s] == 1 if worker w is assigned
to shift s. Since an assignment model always produces integer
solutions, we use continuous variables and solve as an LP. */
for (w = 0; w < nWorkers; ++w)
{
for (s = 0; s < nShifts; ++s)
{
col = xcol(w, s);
sprintf(vname, "%s.%s", Workers[w], Shifts[s]);
error = GRBsetdblattrelement(model, "UB", col, availability[w][s]);
if (error) goto QUIT;
error = GRBsetdblattrelement(model, "Obj", col, pay[w]);
if (error) goto QUIT;
error = GRBsetstrattrelement(model, "VarName", col, vname);
if (error) goto QUIT;
}
}
/* The objective is to minimize the total pay costs */
error = GRBsetintattr(model, "ModelSense", 1);
if (error) goto QUIT;
/* Make space for constraint data */
cbeg = malloc(sizeof(int) * nShifts);
if (!cbeg) goto QUIT;
cind = malloc(sizeof(int) * nShifts * nWorkers);
if (!cind) goto QUIT;
cval = malloc(sizeof(double) * nShifts * nWorkers);
if (!cval) goto QUIT;
sense = malloc(sizeof(char) * nShifts);
if (!sense) goto QUIT;
/* Constraint: assign exactly shiftRequirements[s] workers
to each shift s */
idx = 0;
for (s = 0; s < nShifts; ++s)
{
cbeg[s] = idx;
sense[s] = GRB_EQUAL;
for (w = 0; w < nWorkers; ++w)
{
cind[idx] = xcol(w, s);
cval[idx++] = 1.0;
}
}
error = GRBaddconstrs(model, nShifts, idx, cbeg, cind, cval, sense,
shiftRequirements, Shifts);
if (error) goto QUIT;
/* Optimize */
error = GRBoptimize(model);
if (error) goto QUIT;
error = GRBgetintattr(model, "Status", &status);
if (error) goto QUIT;
if (status == GRB_UNBOUNDED)
{
printf("The model cannot be solved because it is unbounded\n");
goto QUIT;
}
if (status == GRB_OPTIMAL)
{
error = GRBgetdblattr(model, "ObjVal", &obj);
if (error) goto QUIT;
printf("The optimal objective is %f\n", obj);
goto QUIT;
}
if ((status != GRB_INF_OR_UNBD) && (status != GRB_INFEASIBLE))
{
printf("Optimization was stopped with status %i\n", status);
goto QUIT;
}
/* Add slack variables to make the model feasible */
printf("The model is infeasible; adding slack variables\n");
/* Determine the matrix size before adding the slacks */
error = GRBgetintattr(model, "NumVars", &numvars);
if (error) goto QUIT;
error = GRBgetintattr(model, "NumConstrs", &numconstrs);
if (error) goto QUIT;
/* Set original objective coefficients to zero */
for (j = 0; j < numvars; ++j)
{
error = GRBsetdblattrelement(model, "Obj", j, 0.0);
if (error) goto QUIT;
}
/* Add a new slack variable to each shift constraint so that the shifts
can be satisfied */
vbeg = malloc(sizeof(int) * numconstrs);
if (!vbeg) goto QUIT;
vind = malloc(sizeof(int) * numconstrs);
if (!vind) goto QUIT;
vval = malloc(sizeof(double) * numconstrs);
if (!vval) goto QUIT;
vobj = malloc(sizeof(double) * numconstrs);
if (!vobj) goto QUIT;
varnames = calloc(numconstrs, sizeof(char*));
if (!varnames) goto QUIT;
for (i = 0; i < numconstrs; ++i)
{
vbeg[i] = i;
vind[i] = i;
vval[i] = 1.0;
vobj[i] = 1.0;
error = GRBgetstrattrelement(model, "ConstrName", i, &cname);
if (error) goto QUIT;
varnames[i] = malloc(sizeof(char*) * (6 + strlen(cname)));
if (!varnames[i]) goto QUIT;
varnamesct++;
strcpy(varnames[i], cname);
strcat(varnames[i], "Slack");
}
error = GRBaddvars(model, numconstrs, numconstrs,
vbeg, vind, vval, vobj, NULL, NULL, NULL, varnames);
if (error) goto QUIT;
error = GRBupdatemodel(model);
if (error) goto QUIT;
/* Solve the model with slacks */
error = GRBoptimize(model);
if (error) goto QUIT;
error = GRBgetintattr(model, "Status", &status);
if (error) goto QUIT;
if ((status == GRB_INF_OR_UNBD) || (status == GRB_INFEASIBLE) ||
(status == GRB_UNBOUNDED))
{
printf("The model with slacks cannot be solved "
"because it is infeasible or unbounded\n");
goto QUIT;
}
if (status != GRB_OPTIMAL)
{
printf("Optimization was stopped with status %i\n", status);
goto QUIT;
}
printf("\nSlack values:\n");
for (j = numvars; j < numvars + numconstrs; ++j)
{
error = GRBgetdblattrelement(model, "X", j, &sol);
if (error) goto QUIT;
if (sol > 1e-6)
{
error = GRBgetstrattrelement(model, "VarName", j, &sname);
if (error) goto QUIT;
printf("%s = %f\n", sname, sol);
}
}
QUIT:
/* Error reporting */
if (error)
{
printf("ERROR: %s\n", GRBgeterrormsg(env));
exit(1);
}
/* Free data */
free(cbeg);
free(cind);
free(cval);
free(sense);
free(vbeg);
free(vind);
free(vval);
free(vobj);
for (i = 0; i < varnamesct; ++i)
{
free(varnames[i]);
}
free(varnames);
/* Free model */
GRBfreemodel(model);
/* Free environment */
GRBfreeenv(env);
return 0;
}
int main(void)
{
int retcode = 0;
GRBenv *env = NULL;
GRBmodel *model = NULL;
int n, j;
double *obj = NULL;
double *lb = NULL;
double *ub = NULL;
double *x;
int *qrow, *qcol, Nq;
double *qval;
int *cind;
double rhs;
char sense;
double *cval;
int numnonz;
char **names;
n = 9; /** 7 'x' variables, 2 factor variables **/
retcode = GRBloadenv(&env, "factormodel.log");
if (retcode) goto BACK;
/* Create initial model */
retcode = GRBnewmodel(env, &model, "second", n,
NULL, NULL, NULL, NULL, NULL);
if (retcode) goto BACK;
names = (char **) calloc(n, sizeof(char *));
/** next we create the remaining attributes for the n columns **/
obj = (double *) calloc (n, sizeof(double));
ub = (double *) calloc (n, sizeof(double));
lb = (double *) calloc (n, sizeof(double));
x = (double *) calloc (n, sizeof(double));
for(j = 0; j < 7; j++){
names[j] = (char *)calloc(3, sizeof(char));
if(names[j] == NULL){
retcode = 1; goto BACK;
}
sprintf(names[j],"x%d", j);
}
for(j = 7; j < 9; j++){
names[j] = (char *)calloc(3, sizeof(char));
if(names[j] == NULL){
retcode = 1; goto BACK;
}
sprintf(names[j],"y%d", j - 7);
}
obj[0] = -.233; obj[1] = -3.422; obj[2] = -.1904; obj[3] = -.5411;
obj[4] = -.045; obj[5] = -1.271; obj[6] = -0.955;
/** calloc initializes memory to zero, so all other obj[j] are zero **/
/**next, the upper bounds on the x variables **/
ub[0] = 0.6; ub[1] = 0.8; ub[2] = 0.8; ub[3] = 0.5;
ub[4] = 0.5; ub[5] = 0.26; ub[6] = 0.99;
/** the upper bounds on the two factor variables -- we make them large **/
ub[7] = 100; ub[8] = 100;
/** the lower bounds on the factor variables **/
lb[7] = -100; lb[8] = -100;
/* initialize variables */
for(j = 0; j < n; j++){
retcode = GRBsetstrattrelement(model, "VarName", j, names[j]);
if (retcode) goto BACK;
retcode = GRBsetdblattrelement(model, "Obj", j, obj[j]);
if (retcode) goto BACK;
retcode = GRBsetdblattrelement(model, "LB", j, lb[j]);
if (retcode) goto BACK;
retcode = GRBsetdblattrelement(model, "UB", j, ub[j]);
if (retcode) goto BACK;
}
/** next, the quadratic -- there are 11 nonzeroes: 7 residual variances plus the 2x2
factor covariance matrix**/
Nq = 11;
qrow = (int *) calloc(Nq, sizeof(int)); /** row indices **/
qcol = (int *) calloc(Nq, sizeof(int)); /** column indices **/
qval = (double *) calloc(Nq, sizeof(double)); /** values **/
if( ( qrow == NULL) || ( qcol == NULL) || (qval == NULL) ){
printf("could not create quadratic\n");
retcode = 1; goto BACK;
}
qval[0] = 10.0; qrow[0] = 0; qcol[0] = 0;
qval[1] = 20.0; qrow[1] = 1; qcol[1] = 1;
qval[2] = 30.0; qrow[2] = 2; qcol[2] = 2;
qval[3] = 40.0; qrow[3] = 3; qcol[3] = 3;
qval[4] = 50.0; qrow[4] = 4; qcol[4] = 4;
qval[5] = 60.0; qrow[5] = 5; qcol[5] = 5;
qval[6] = 70.0; qrow[6] = 6; qcol[6] = 6;
qval[7] = 100.0; qrow[7] = 7; qcol[7] = 7;
qval[8] = 200.0; qrow[8] = 8; qcol[8] = 8;
qval[9] = 0.1; qrow[9] = 7; qcol[9] = 8;
qval[10] = 0.1; qrow[10] = 8; qcol[10] = 7;
retcode = GRBaddqpterms(model, 11, qrow, qcol, qval);
if (retcode) goto BACK;
/** now we will add one constraint at a time **/
/** we need to have a couple of auxiliary arrays **/
cind = (int *)calloc(n, sizeof(int)); /** n is over the top since no constraint is totally dense;
but it's not too bad here **/
cval= (double *)calloc(n, sizeof(double));
/** two factor constraints, first one is next**/
cval[0] = 1.508; cval[1] = .7802; cval[2] = 1.8796;
cval[3] = 4.256; cval[4] = 1.335; cval[5] = 2.026; cval[6] = 1.909;
cval[7] = -1;
for(j = 0; j < 7; j++) cind[j] = j;
cind[7] = 7;
numnonz = 8;
rhs = 0;
sense = GRB_EQUAL;
retcode = GRBaddconstr(model, numnonz, cind, cval, sense, rhs, "first_constraint");
if (retcode) goto BACK;
/** second factor constraint **/
cval[0] = 4.228; cval[1] = 1.2945; cval[2] = .827;
cval[3] = 2.149;
cval[4] = 2.353; cval[5] = 0.3026; cval[6] = 1.487;
cval[7] = -1;
for(j = 0; j < 7; j++) cind[j] = j; /** redundant! but let's keep it here so that we know it
will be used **/
cind[7] = 7;
numnonz = 8;
rhs = 0;
sense = GRB_EQUAL;
retcode = GRBaddconstr(model, numnonz, cind, cval, sense, rhs, "second_constraint");
if (retcode) goto BACK;
/** sum of x variables = 1 **/
cval[0] = 1.0; cval[1] = 1.0; cval[2] = 1.0;
cval[3] = 1.0; cval[4] = 1.0; cval[5] = 1.0; cval[6] = 1.0;
for(j = 0; j < 7; j++) cind[j] = j;
numnonz = 7;
rhs = 1.0;
sense = GRB_EQUAL;
retcode = GRBaddconstr(model, numnonz, cind, cval, sense, rhs, "convexity");
if (retcode) goto BACK;
retcode = GRBupdatemodel(model);
if (retcode) goto BACK;
/** optional: write the problem **/
retcode = GRBwrite(model, "factorqp.lp");
if (retcode) goto BACK;
retcode = GRBoptimize(model);
if (retcode) goto BACK;
/** get solution **/
retcode = GRBgetdblattrarray(model,
GRB_DBL_ATTR_X, 0, n,
x);
if(retcode) goto BACK;
/** now let's see the values **/
for(j = 0; j < n; j++){
printf("%s = %g\n", names[j], x[j]);
}
GRBfreemodel(model);
GRBfreeenv(env);
BACK:
printf("\nexiting with retcode %d\n", retcode);
return retcode;
}